3% is not bad at all though. It is overall FPS though. 2 x 560ti is never going to be utilized fully on a 60hz monitor.

If you have a 120hz, I am not sure that any games will be affected either. Maybe at stock clocks they could be.

240hz is another story. You would see it. What is your monitor running? 60 in 1080p?

EDIT: I love Nvidia, but I would not shy away from looking at AMD 69xx cards. They really have some good ones.

EDIT 2: You are not going to believe this. I just looked at GPU-Z and it says mine are running x8 which is what they are supposed to run. When I first installed SLI Hack, GPU-Z said x4 for both. I also got a Windows pop-up stating the video cards could perform better if they were plugged into a faster PCIe slot. Now I am confused!

Nvidia UCP still has a suggestion to plug the cards into a faster PCI slot though. Maybe that is only suggesting x16.

I have 2 PCIe slots. Slot 1 always operates at x8 no matter what. Slot 2 can operate at x16 if I stick a VGA Switch Card into Slot 1. In other words, I can run 1 PCIe slot at x16 if I bridge the 2 slots together with the switch card.

So, x8 with 2 cards is what it is supposed to run at, even if it was SLI ready or I used AMD cards.

I would not worry about it. Even if it does downclock your PCIe slots, it will not affect your gaming. 3% with one card might in a few games though. Barely noticable.

I hear you on the prices of those AMD 69xx cards. Most of the benchmark results that show the 6950 or 6970 spanking the 560ti have a core clock of 900 versus a 560ti at 700. Not really an equal comparison! They are close at the same clock speeds. Close enough not to invest the extra money!